1. Field
The present disclosure relates generally to the blades of a rotorcraft and, in particular, to a system for moving the blade of a rotorcraft. Still more particularly, the present disclosure relates to an apparatus, system, and method for pitching and twisting the blade of a rotorcraft using an actuation system that is external to the blade and located at a root portion of the blade.
2. Background
A rotorcraft is a type of aircraft that operates using the lift generated by blades revolving around a mast. A helicopter is an example of a rotorcraft. The blades of a rotorcraft may be part of a rotor system. In some cases, these blades are referred to as rotor blades. The blades of a rotorcraft may be pitched and/or twisted during operation to generate the lift needed to allow the rotorcraft to hover and/or fly.
Pitching a blade means rotating the blade about an axis through the length of the blade. Pitching may be used to control the direction in which the maximum amount of thrust is generated by the rotorcraft. Twisting a blade means twisting the blade about an axis extending from one end of the blade to another end of the blade. Typically, a blade is twisted with respect to the axis about which the blade rotates or pitches. Changing the amount of twisting of the blades of a rotorcraft in different flight regimes may improve the efficiency of the rotorcraft. The different flight regimes for a rotorcraft may include hover, climb, descent, and forward flight. Further, the rotorcraft may perform maneuvers that may include some combination of the above regimes.
Some currently available systems for twisting a blade use piezoelectric actuators mounted to the blade. However, these types of actuators may require a higher voltage to be supplied to the actuators than desired. Further, supplying voltage to these actuators may require that power lines be run along the length of the blade to reach the actuators mounted on the blade.
Other currently available systems for twisting a blade use shape memory alloys. However, shape memory alloys may have slower actuation times than desired. Consequently, changing the degree of twisting of a blade may take longer than desired.
Further, some currently available systems for twisting a blade may use actuators that are heavier than desired and/or that change the overall contour of the blade when mounted to the blade more than desired. This increased weight and/or change in contour may reduce the performance of the blade during operation of the rotorcraft more than desired. Therefore, it would be desirable to have an apparatus, system, and method that take into account at least some of the issues discussed above, as well as other possible issues.